Electrical connector



INVENTOR Oct. 5, 1965 N- c. GRAEFF ELECTRICAL CONNECTOR Filed April 12, 1963 Nolzwooo C. GQHEFF United States Patent 3,210,719 ELECTRICAL CONNECTOR Norwood C. Graetf, Port Trevorton, Pa., assignor to AMP Incorporated, Harrisburg, Pa. Filed Apr. 12, 1963, Ser. No. 272,756 2 Claims. (Cl. 339-95) The present invention relates to a new and improved wire terminal or connector used in connecting a wire to a terminal block or binding post, and particularly relates to such a connector wherein a wire conductor may be locked to the connector without soldering or crimping. The new connector comprises a tab having a wire-engaging portion on one end thereof, into which portion a conductor wire may be inserted, to effect a secure mechanical and electrical connection.

One of the objects of the present invention is to provide an improved solderless wire connector which fastens to a wire and has locking means to hold it thereon and to prevent its accidental removal.

Another object is to provide an improved wire connector which is readily and easily applied to a wire conductor Without the aid of special tools.

These and other objects and advantages will become apparent when the description of a preferred form of the invention is read in conjunction with the accompanying drawings wherein:

FIGURE 1 is an enlarged, perspective view of a punched or stamped metal blank from which a connector may be formed;

FIGURE 2 is an enlarged, perspective view of the wire-engaging member of the connector;

FIGURE 3 is an enlarged, perspective view of the assembled connector before a wire is connected therewith;

FIGURE 4 is an enlarged view similar to FIGURE 3, illustrating a conductor secured to the connector;

FIGURE 5 is a sectional view taken along the lines 5-5 of FIGURE 3;

FIGURE 6 is a sectional view taken along the lines 66 of FIGURE 4;

FIGURE 7 is a top plan view of the device of FIG- URE 4; and

FIGURE 8 is a sectional view representing another embodiment of the invention.

As is shown in FIGURE 1, the connector C may be formed from a sheet metal tab 2. The tab 2 has a large hole 4 punched through a section comprising one side of the wire engaging portion of the completed connector. A small hole 6 is punched through another section on the other side of the wire engaging portion. The diameter of hole 6 is slightly greater than the largest conductor to be accommodated therein. The portion of the tab adjacent hole 6 comprises the current coupling member 8 When the tab is finally formed. Aperture 10 is adapted to receive a binding post P (FIGURE 3).

As shown in FIGURE 2, a metal blank 12, which is substantially thinner in cross-section than tab 2, and which is formed from resilient metal, e.g.: full hard beryllium copper comprises the wire engaging member of the connector C. Metal blank 12 has a series of radial slots 14 cut therein. The outer ends 15 of the slots 14 form an imaginary circle on the blank. The inner ends 17 of slots 14 converge in the center of the blank. Slots 14 form a nest of triangular-shaped spring fingers 16, having their base legs 18 integrally connected with the blank 12 to serve as hinges. The apices 20 of fingers 16 converge at the center of blank 12. The spring fingers 16 form a section which permits a wire to be inserted therein.

In assembly (FIGURE 3), blank 12 is placed onto tab 2 so that apices 20 are concentric with small hole 6,

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whereafter the portion of tab 2 having the large hole 4 therein is folded over blank 12, as shown. This arrangement provides the wire engaging portion to secure a wire conductor to tab 2.

To make an electrical connection, the connector C is fastened to the binding post P, which extends through the aperture 10 and is locked thereon by a nut N. A wire conductor is introduced into small hole 6, as shown in FIGURES 4 and 5. As the wire W enters blank 12, spring fingers 16 are forced to bend upwardly (FIGURE 6) on hinges 18. The wire W will spread fingers 16, thus spring biasing the fingers 16 outwardly and positively locking the conductor therein. The fingers 16 scrape oxidation and other foreign materials from the conductor, thereby providing a better electrical connection. The large hole 4 permits spring fingers 16 to bend upwardly as shown. The large hole 4 is oversize to allow a number of different size wires in a given wire range to be connected to one size connector.

After inserting the conductor W into wire-engaging member 12 (FIGURES 4 and 5), any attempt to remove the conductor will be resisted by the spring bias of the fingers. Thus, some of the conductor strands will become wedged into slots 14 (FIGURES 4 and 6) to provide larger contact areas between the wire and the connector, and enhance the electrical connection therebetween. The wire cannot be easily withdrawn from the connector, as the slightest withdrawing movement will increase contact pressures therebetween, thus tightening the connection.

In the embodiment of the invention illustrated in FIG- URE 8, a connector C generally similar to that of FIG- URES 1 through 7 is shown. This connector differs primarily in that it is made in one piece. The spring fingers 16' are formed into one end of the tab, which end is folded over small hole 6'. The area X of the contactengaging member containing fingers 16' may be skived or counterbored, as shown in FIGURE 8, to reduce the thickness of fingers 16. By this means, fingers 16' will be substantially thinner than their surrounding portion, thus increasing their flexibility to permit them to receive the wire conductor as hereinbefore described.

It will, therefore, be appreciated that the aforementioned and other desirable objectives have been achieved; however, it should be emphasized that the particular embodiments of the invention, which are shown and described herein, are intended as merely illustrative and not as restrictive of the invention.

I claim:

1. In a solderless connector for making a mechanical and electrical connection to a stranded wire, a tab provided with a protruding blade and a folded portion, a conductive metal member within said folded portion and having a series of radial slots forming triangular-shaped spring fingers with converging apices, said folded portion having a first wire-receiving hole of a diameter substantially the same as that of the stranded wire and a second wire-receiving hole of a diameter substantially greater than that of the wire, said wire-receiving holes being in alignment with said converging apices and adapted to receive said stranded wire upon insertion into the first wire-receiving hole, said spring fingers being adapted to flex in said second Wire-receiving hole, said radial slots being adapted to open by insertion forces from said stranded wire and receive separate strands of said stranded wire and wedge the strands into tight engagement between adjacent spring fingers whereby the stranded wire is mechanically and electrically secured therein.

2. A connection between a solderless connector and a stranded wire, comprising a connector including a tab provided with a protruding blade and a folded portion, conductive member within said folded portion and having a series of radial slots forming trianuglar-shaped spring fingers with converging apices, said folded portion having a first wire-receiving hole of the diameter substantially the same as that of the stranded wire and a second wire-receiving hole of a diameter substantially greater than that of the wire, said wire-receiving holes being in alignment with said converging apices, a stranded wire inserted into the first wire-receiving hole, said spring fingers in flexed position in said second wire-receiving hole and said radial slots held in open position by said stranded wire, and said strands being wedged into tight stranded wire is mechanically and electrically secured therein.

References Cited by the Examiner UNITED STATES PATENTS JOSEPH D. SEERS, Primary Examiner.

engagement between adjacent spring fingers whereby the 15 W, DONALD MILLER, E i 

2. A CONNECTION BETWEEN A SOLDERLESS CONNECTOR AND A STRAND WIRE, COMPRISING A CONNECTOR INCLUDING A TAB PROVIDED WITH A PROTRUDING BLADE AND A FOLDED PORTION CONDUCTIVE MEMBER WITHIN SAID FOLDED PORTION AND HAVING A SERIES OF RADIAL SLOTS FORMING TRIANGULAR-SHAPED SPRING FINGERS WITH CONVERGING APICES, SAID FOLDED PORTION HAVING A FIRST WIRE-RECEIVING HOLE OF THE DIAMETER SUBSTANTIALLY THE SAME AS THAT OF THE STRANDED WIRE AND A SECOND WIRE-RECEIVING HOLE OF A DIAMETER SUBSTANTIALLY GREATER THAN THAT OF THE WIRE, SAID WIRE-RECEIVING HOLES BEING IN ALIGNMENT WITH SAID CONVERGING APICES, A STRANDED WIRE INSERTED INTO THE FIRST WIRE-RECEIVING HOLE, SAID SPRING FINGERS IN FLEXED POSITION IN SAID SECOND WIRE-RECEIVING HOLE AND SAID RADIAL SLOTS HELD IN OPEN POSITION BY SAID 